From U.S. Pat. No. 4,256,947 it is known that the customary assembly line, which is characterized by a straight-through transfer line, and can be broken up individual work stations arranged side by side. The workpiece elements to be connected and welded together are first retained by a workpiece carrier, which is guided into the input station of the pertinent work station along a prepared guide path by a suitable transport device. From there, the workpiece carrier arrives at a work position where, by means of industrial robots, welding in the sense of tacking or finish welding is carried out. By means of switches, the correlation of the guided work piece carrier with a given work position among several lying side by side can be controlled.
Although the above teaching permits the flexible completion of semi-finished vehicle bodies, the equipment required is considerable, the floor space requirements are extensive, and the transportation of the workpieces involves problems.